Well, you said, "viable in the here and now" ... and, I would say that sales "trending upward" sounds viable, to me. "How long they should wait to start making changes" is a different question ... another is whether closing 63 stores and laying off thousands of people is the only change they could make to remain viable.
When you're asking about Wal-Mart's options, as if they are only making the hard choices necessary to keep their business afloat -- I just wanna point out, not only do they still kick the crap out of everybody in terms of profit (including Amazon) as they have for decades now, but the Waltons remain the richest family in the world, as the owners of this business.